#include<iostream>
 using namespace std;
 class A
 {
 public:
     A(int a = 2, int b = 3)
         : _a(a)
         , _b(b)
     {
         cout << "A()" << endl;
         cout << "_a = " << _a << "_b = " << endl;
     }
     A(A& temp)
     {
         _a = temp._a;
         _b = temp._b;
     }
     ~A()
     {
         cout << "~A()" << endl;
     }
 private:
     int _a;
     int _b;
 };
int main()
{
     A aa1;
     A aa2(10, 20);
     A aa3(aa2);
     return 0;
}